ARMY TM 10-1670-275-23&PAIR FORCE TO 13C5-25-2NAVY NAVAIR 13-1-26Code ExplanationXA - Do not requisition an "XA"-coded item. Order its next higher assembly. (Also, refer to the NOTE below.)XB - If an "XB" item is not available from salvage, order it using the CAGE Code and part number given.XC - Installation drawing, diagram, instruction sheet, field service drawing, that is identified by manufacturer'spart number.XD - Item is not stocked. Order an "XD"-coded item through normal supply channels using the CAGE Codeand part number given, if no NSN is available.NOTECannibalization or controlled exchange, when authorized, may be used as a sourceof supply for items with the above source codes, except for those source coded"XA".(2) MaintenanceCode. Maintenance codes tell you the level(s) of maintenance authorized to USE andREPAIR support items. The maintenance codes are entered in the third and fourth positions of the SMR codeas follows:(a) The maintenance code entered in the third position tells you the lowest maintenance levelauthorized to remove, replace, and use an item. The maintenance code entered in the thirdposition will indicate authorization to the following levels of maintenance.CodeApplication/ExplanationC - Crew or operator maintenance done within unit/AVUM maintenance.O - Unit level VAVUM maintenance can remove, replace, and use the item.F - Direct support/AVIM maintenance can remove, replace, and use the item.H - General support maintenance can remove, replace, and use the item.L - Specialized repair activity can remove, replace, and use the item.D - Depot can remove, replace, and use the item.(b) The maintenance code entered in the fourth position tells whether or not the item is to berepaired and identifies the lowest maintenance level with the capability to do completerepair (i.e., perform all authorized repair functions). This position will contain one of thefollowing maintenance codes.C-3